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Home > Applications > EPR > LTR


  • Overview
  • Specifications
  • Drawings
  • Pictures
LTR Cryostat shown with Instrumentation Cable

The LTR is specifically designed for X-band EPR, and ESR measurements. The sample is cooled by a jet of liquid helium inside a quartz cuvette. We offer glassware designed to fit into the Bruker cavity, as well as Varian and JEOL glassware sets.

LTR benefits from some of the features that set the ARS manufactured LT3 cryostats apart from all other flow cryostats, including the coaxial shield flow transfer line and impedance valve.

Click here to see more Advanced Research Systems flow cryostats.

Click here to see more Advanced Research Systems cryostats for Electron Paramagnetic Resonance (EPR).

  • Glassware to fit into Bruker cavity
  • Bruker cavity adapter
  • Mounting arrangement for Bruker magnet
  • Liquid helium flow
  • Co-axial shield flow transfer line
  • 4.2 K liquid helium operation
  • 0.75 LL/hr liquid helium consumption at 4.2 K
  • Precision flow control
  • Fully customizable
Typical Configuration
  • Cold head (LTR)
  • Co-axial shield flow liquid helium transfer line
  • Stainless steel instrumentation skirt
  • Dewar adapter
  • Flow meter panel for helium flow control and optimization
  • Bruker cavity sdapter
  • Glassware to fit into Bruker cavity
  • Instrumentation for temperature measurement and control:
    • 10 pin feedthrough
    • 36 ohm thermofoil heater
    • Gold Chromel thermocouple for temperature control
    • Gold Chromel thermocouple for accurate measurement
  • Temperature controller
Options and Upgrades

The ARS Advantage

Co-axial Shield Flow
A Schematic Representation of the Coaxial Shield Flow Transferline

Conventional helium flow cryostats utilize a capillary tube in a vacuum jacket with super insulation to reduce the radiant heat load.  However as the helium absorbs radiant heat, the liquid is vaporized and forms bubbles of gas which have a larger volume than the liquid, thus forming a temporary block to the flow of the liquid. This is called “vapor binding.”  At the delivery end of the transfer line this results in the liquid/gas mixture being delivered in spurts, with accompanying pressure and temperature cycling.

The coaxial flow transfer line incorporates a shield flow surrounding the tip flow for the entire length of the transfer line. The entrance to the coaxial shield flow tube is provided with a nozzle which results in a pressure and corresponding temperature drop in the shield flow. This cools the tip flow in the center tube, which prevents boiling and gas bubble formation in the helium, even at very low flow rates.  The helium is delivered at the sample end with the desired temperature stability and low vibrations.

Liquid Helium Flow Cryostat Specifications

Cryostat Model LTR
   Cryogen Liquid helium
   Base Temperature 4.2 K < 2 K with pumping
   Nominal Helium Consumption at 4.2 K 0.75 LL/hr
    Cooldown Time 20 min to 4.2 K
    Maximum Temperature 350 K
LTR Drawing

Cryostat for X-band EPR, and ESR measurements

Click on the images for full size.